Radio frequency switches of the diode network type are of general utility. In television receivers, for example, such switches are frequently used to selectively couple antenna and auxiliary signal sources to the receiver tuner and to provide a so-called "loop through" function for switching the antenna input to another device such as a cable decoder or a video cassette recorder. An example of an RF switch providing these functions is described by Strammello, Jr. in U.S. Pat. No. 4,400,735 entitled MULTI-COMPONENT VIDEO SYSTEM CONTROLLER which issued Aug. 23, 1983. Each individual RF switch in the Strammello Jr. controller employs series and shunt diodes connected in a T-network configuration. When the switch is "OFF" (i.e., not passing a signal) the series diodes are reverse biased and exhibit a small capacitance while the shunt diodes are forward biased and exhibit a relatively low resistance thereby attenuating signal flow between input and output ports of the switch. The switch is turned "ON" by applying forward bias to the series diodes and reverse bias to the shunt diodes of the T-network. To provide high attenuation in such a switch generally requires a relatively high reverse bias for the series diodes and a large forward bias current for the shunt diode. These measures, however, have the attendant disadvantage of relatively high power dissipation. Additionally, cascading diode network sections to improve the attenuation is expensive and undesirably increases the switch transmission losses in the ON state.
Another example of a diode network RF switch is described by Snow in U.S. Pat. No. 3,047,741 entitled MULTIPLE CHANNEL ELECTRONIC SWITCHING CIRCUIT which issued July 31, 1962. The Snow switch employs series type diode networks for RF switching and features a latching circuit comprising Shockley or NPNP type trigger diodes for generating the switch bias voltage. By this means the switch is provided with a "memory", so to speak, for maintaining the switch in its ON or Off state and so the switch requires only momentary applications of drive current to change its state. The attenuation of the switch in the off state suffers, however, because of the lack of a shunt branch in the switch and relatively complex gating circuits are required for controlling the trigger diodes.